Overall I'd probably give the edge to the Retina with the f2 Schneider lens. Bear in mind that you're dealing with cameras of two different eras (the earliest Retinas were built in the 1930s, the Konica S2 was in the 60s). The Retina was also a much higher-end camera than the S2 - they were meant to compete with Leicas and Zeiss Ikons and were priced accordingly when new. Today's pricing still indicates this difference- most S2s can be had for under $50. Retinas run from $100-300 or even more depending on condition, model and accessories.

I have both a Retina big C III and the Konica Auto S. The Retina is a great camera, the F 2 lens is very sharp wide open, stopped down to 5.6 or 8 really very good, somewhat diffcult to load, setting the frame counter is chore, the film advance and the coupled shutter speed and f stop take some getting use to. The 80mm and 35mm lens are a wast of money, very slow, hard to carry, takes time to swap out, and not all that sharp. The Retina was my first 35mm, my aunts bought it for me for a combo brithday and Xmas present while I was still in high school. While in College I moved up to a Spotmatic but carried the Retina as my spare body for years. Konica made some of the best lens I have ever used. For ease of use and a pocket camera my nod goes to the Konica.